Powerless signal generation for use in conjunction with a powerless position determination device

ABSTRACT

A reflector and a powerless signal generator mechanism are incorporated into a single powerless pointing device. A light source generates a light signal, and the reflector incorporated within the powerless pointing device reflects the light signal back to a image collection system of a computer. Image data is generated, and is used to generate position data relating to the position of the reflector. The position is correlated to a position on a graphical user interface. A user action activates the powerless signal generator mechanism, generating a signal. The signal can be, for example, in the form of a sound pulse having one or more predetermined frequencies or an RF signal generated by a piezo-electric transducer.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention is a Continuation-in-Part of U.S. patent application Ser. No. 11/111,444 filed on Apr. 21, 2005, and entitled “Position Determination Utilizing a Cordless Device,” which is assigned to the assignee of the current invention. The present invention incorporates by reference U.S. patent application Ser. No. 10/739,831 filed on Dec. 18, 2003 and U.S. patent application Ser. No. 10/843,517 filed on May 10, 2004, both of which were entitled “Method and System for Wavelength-Dependent Imaging and Detection Using a Hybrid Filter” and assigned to the assignee of the current invention.

BACKGROUND OF THE INVENTION

A conventional computer mouse functions both to track a position across a graphical user interface (GUI) and to input commands into the computer, usually relating to a word, icon, or text section on which the tracking system was located at the time of the input command. A conventional computer mouse requires power that typically comes from one of two sources. In a first “wired” form, a power cord tethers the mouse to the computer, thereby providing power for both the tracking function and the input command function, while also providing a signal path for both the position tracking system and the input command. The power cord, however, restricts freedom of movement for the user. In a second “wireless” form, an on-board power source such as a battery provides power for these functions. The signals for both the tracking and input command functions are transmitted through free space in the form of RF signals. An on-board power source, however, requires constant recharging or replacement.

A technique for powerless position tracking is disclosed in U.S. patent application Ser. No. 11/111,444 entitled “Position Determination Utilizing a Cordless Device” filed on Apr. 21, 2005. The pointing device disclosed therein has a reflector and interfaces with a computer system having a light source, an image collection system, a processor, and a graphical user interface (GUI). The light source generates a light signal and the reflector within the pointing device reflects a portion of the light signal back to the image collection system, which correlates a position of the reflector to a position on the GUI. The correlation is continuously updated by a processor. Because a reflector is a passive element that does not require any power, a pointing device that utilizes a reflector does not need to be tethered to a computer system or equipped with a battery. Because the “point and click” functions are so tightly interrelated when used in conjunction with a GUI, it is desirable for the “pointing” and “clicking” functions to be integrated into a single powerless device.

SUMMARY OF THE INVENTION

A pointing device has a reflector and a powerless signal generator mechanism for generating a signal in response to a user action. The pointing device is used in conjunction with a computer system. The computer system includes an image collection system for generating image data which includes an indication of the reflector, a processor configured to use the image data to generate position information related to the reflector, and a receiver configured to detect the signal generated by the powerless signal generator mechanism. The powerless signal generator mechanism includes a signal generator activated by a user action. The signal is generated to trigger a function in the computing system. In contrast to prior art devices, wherein the energy necessary to generate the desired signal is supplied by an external power source such as a battery or commercial AC power, a unique feature of the present invention is that a user action supplies the energy necessary to generate the desired signal. No additional power source is needed to generate the desired signal. The signal generated by the powerless signal generator mechanism is received by the receiver of the computer where it is converted into a digital form that can be used by the processor to, for example, navigate within a GUI.

The powerless signal generator mechanism can be in the form of a pulse generator that generates a sound pulse having one or more predetermined frequencies, or a piezo-electric transmitter that generates an RF signal. A pointing device may include multiple powerless signal generator mechanisms that are configured to generate different signals. A multi-signal embodiment allows the pointing device of the present invention to duplicate the functionality of a conventional mouse having, for example, “right click” and “left click” input command functions. By generating command signals without the aid of an external power cord or on-board power source, the manually activated input command function can operate synergistically with a powerless pointing device to duplicate the functions of a conventional computer mouse, but without the need to be electrically coupled to an external power source, nor the need for an on-board power supply such as a battery.

Other aspects and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrated by way of example of the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a system for generating position information that includes a retroreflector, an image collection system, and a processor.

FIGS. 2 and 3 illustrate the detection angle, the on-axis illumination angle, and the off-axis illumination angle in the image collection system of FIG. 1.

FIG. 4 depicts light of wavelength λ1 and wavelength λ2 that is incident on an imager after reflecting off of a retroreflector and any miscellaneous objects.

FIG. 5 illustrates the basic operation of the system of FIG. 1.

FIG. 6 is an exemplary graph of difference image data with the intensity difference values on the x-axis and the number of data points collected at each intensity difference value on the y-axis.

FIG. 7 depicts an alternative embodiment of the image collection system from FIG. 1 that includes one imager and multiple on-axis and off-axis light sources.

FIG. 8 depicts an embodiment of an image collection system that includes two imagers and a single light source.

FIG. 9 depicts an embodiment of the image collection system that includes two imagers and light sources that provide light of two different wavelengths.

FIG. 10 is a perspective view of the image collection system of FIG. 9 configured in an epipolar geometry.

FIG. 11 depicts an embodiment of an image collection system that includes on-axis and off-axis light sources and a wavelength-selective filter formed over the retroreflector.

FIG. 12 depicts an exemplary embodiment of an image collection system in which the light sources of two different wavelengths have the same, or roughly the same, illumination angle and in which a wavelength-selective filter is formed over the retroreflector.

FIG. 13 depicts an embodiment of an image collection system that includes one imager and a single light source.

FIG. 14 depicts another embodiment of a single light source image collection system.

FIG. 15 depicts an embodiment of a system for generating position information that utilizes a reflector other than a retroreflector.

FIGS. 16A and 16B depict an embodiment of a pointing device that incorporates a mechanism for shielding and revealing a retroreflector.

FIGS. 17A and 17B depict another embodiment of a pointing device that incorporates a mechanism for shielding and revealing multiple retroreflectors.

FIGS. 18A and 18B depict an embodiment of a pointing device that includes a retroreflector embedded into a cavity of a pointing device.

FIG. 19A depicts a top view of an imager that includes a checkerboard filter pattern.

FIG. 19B depicts a side view of the imager from FIG. 19A with a hybrid filter over the imager.

FIG. 20 depicts a portable computer configured with an image collection system that includes two light sources and one imager embedded into the housing of the computer.

FIG. 21 depicts a portable computer configured with an image collection system that includes two light sources and two imagers embedded into the housing of the computer.

FIG. 22A a front view of an image collection system in which an imager and light sources are incorporated into a free standing housing.

FIG. 22B depicts a side view of the image collection system of FIG. 22A.

FIG. 23 depicts a process flow diagram of a method for generating position information.

FIG. 24 depicts a process flow diagram of another method for generating position information.

FIGS. 25A and 25B depict an example of a retroreflector that has an orientation-specific shape.

FIGS. 26A and 26B depict an example of multiple retroreflectors configured in an orientation-specific pattern on the surface of a pointing device.

FIGS. 27A and 27B depict an example of multiple retroreflectors that have different shapes.

FIGS. 28A-28C depict an example of a retroreflector that is integrated into a device that has an orientation-specific structural feature.

FIGS. 29A-29C depict an embodiment of a pointing device that is similar to the pointing device described with reference to FIGS. 28A-28C except that it includes a retroreflector that is not subject to the orientation-specific structural feature of the pointing device.

FIGS. 30A and 30B depict an embodiment of a pointing device in which multiple retroreflectors are used in conjunction with orientation-specific structural features to enable the generation of more detailed orientation information.

FIG. 31A depicts a side view of the pointing device from FIGS. 30A and 30B in which the cavities and retroreflectors are oriented relative to a beam of light such that all of the retroreflectors are illuminated.

FIG. 31B is a front view of the pointing device from FIG. 31A in which the illumination of all of the retroreflectors is represented by the filled in dark circles.

FIG. 32A depicts a side view of the pointing device from FIGS. 30A and 30B in which the cavities and retroreflectors are oriented relative to the beam of light such that only some of the retroreflectors are illuminated.

FIG. 32B is a front view of the pointing device from FIG. 32A in which the illuminated retroreflectors are represented by filled in dark circles and the non-illuminated retroreflectors are represented by the un-filled in circles.

FIGS. 33A and 33B depict an example of a pointing device that utilizes an orientation-specific pattern of retroreflectors as described with reference to FIGS. 26A and 26B in conjunction with a pattern of retroreflectors that is integrated into orientation-specific features of the pointing device as described with reference to FIGS. 30A-32B.

FIG. 34 depicts an embodiment of a cavity in a pointing device and a retroreflector that is attached at the bottom of the cavity.

FIG. 35 depicts a process flow diagram of a method for generating orientation information.

FIG. 36 depicts a process flow diagram of a method for generating position information and orientation information.

FIG. 37 depicts a pointing device with a reflector and a powerless signal generator mechanism.

FIG. 38 depicts the pointing device of FIG. 37 and a computer system that includes an image collection system.

FIG. 39 depicts an embodiment of the pointing device of FIG. 37 wherein the powerless signal generator mechanism is a pulse generator.

FIG. 40A depicts a side elevation view of an embodiment of the pulse generator of FIG. 39 prior to actuation.

FIG. 40B depicts the pulse generator of FIG. 40A during actuation, and immediately prior to hammer release.

FIG. 41 illustrates an embodiment of the pulse generator of FIG. 39 having a plurality of sonic resonators that correspond to a predetermined digital value.

FIG. 42 is a side elevation view of a piezo-electric signal generator embodiment of the pointing device of FIG. 37.

FIG. 43 depicts an embodiment of the piezo-electric signal generator from FIG. 42.

FIG. 44 depicts a process flow diagram of a method of generating position information relating to a pointing device.

Throughout the description similar reference numbers may be used to identify similar elements.

DETAILED DESCRIPTION

Within the following specification, FIGS. 1-36 and the related description are directed to a reflector based pointing device as disclosed in U.S. patent application Ser. No. 11/111,444 and entitled “Position Determination Utilizing a Cordless Device,” filed on Apr. 21, 2005. The focus of the present invention as found in the appended claims is directed to FIGS. 37-44, and the description related thereto, which incorporates a powerless signal generator mechanism described in conjunction with FIGS. 37-44 with a reflector based pointing device.

A pointing device has a reflector and a powerless signal generator mechanism for generating a signal in response to a user action. The pointing device is used in conjunction with a computer system. The computer system includes an image collection system for generating image data that includes an indication of the reflector, a processor configured to use the image data to generate position information related to the reflector, and a receiver configured to detect the signal generated by the powerless signal generator mechanism.

The powerless signal generator mechanism includes a signal generator activated by a user action. The signal generated by the powerless signal generator mechanism is received by the receiver of the computer system where it is converted into a digital form that can be used by the processor to navigate, for example, within a GUI.

The powerless signal generator mechanism can be in the form of a pulse generator that generates a sound pulse having one or more predetermined frequencies or a piezo-electric transmitter that generates an RF signal. A pointing device may include multiple powerless signal generator mechanisms that are configured to generate different signals in response to different user actions. A multi-signal embodiment allows the pointing device of the present invention to duplicate the functionality of a conventional mouse having, for example, “right click” and “left click” input commands functions. By generating command signals without the aid of an external power cord or on-board power source, a manually activated input command function can operate synergistically with a powerless pointing device, allowing the powerless pointing device to duplicate all of the functions of a conventional computer mouse, but without the need to be electrically coupled to an external power source, nor the need for an on-board power supply such as a battery.

FIG. 1 depicts a system 100 for generating position information that includes a retroreflector 102, an image collection system 104A, and a processor 106. In the embodiment of FIG. 1, the image collection system includes an imager 108 and first and second light sources 110, 112 that output light 114, 116 having different wavelengths. The first light source 110 is located closer to the imager than the second light source 112 and the two light sources and the imager are located in the same plane. The first light source is referred to herein as the “on-axis” light source and the second light source is referred to herein as the “off-axis” light source.

The terms “on-axis” and “off-axis” as used herein are described with reference to FIGS. 2 and 3. The angle at which light from a light source illuminates the retroreflector 102 is referred to as the illumination angle. Referring to FIG. 2, the illumination angle is measured relative to a plane (as indicated by dashed line 120) that is coplanar with the plane of the major surface of the imager 108. The illumination angle of light source 110 is identified as θ_(i1) and the illumination angle of light source 112 is identified as θ_(i2). The angle at which light 118 reflected from the retroreflector is incident on the imager is referred to as the detection angle. The detection angle is identified as θ_(d) and is measured relative to the same plane as the illumination angle. In the case of two illumination angles, θ_(i1) and θ_(i2), the term “on-axis” applies to the light source or the illuminating beam whose illumination angle has the smaller difference from the detection angle, θ_(d), and the term “off-axis” refers to the light source or the illumination beam whose illumination angle has the largest difference from the detection angle. Referring to FIG. 2, the relationship of the illumination and detection angles is mathematically expressed as: |θ_(i1)−θ_(d)|<|θ_(i2)−θ_(d)|.

FIG. 3 illustrates changes in the illumination and detection angles that occur as the retroreflector 102 moves relative to the imager 108 and the two light sources 110, 112. Although the illumination and detection angles change as the retroreflector moves, the difference between the on-axis illumination angle and the detection angle remains smaller than the difference between the off-axis illumination angle and the detection angle, |θ_(i1)−θ_(d)|<|θ_(i2)−θ_(d)|. Given this relationship between the illumination and detection angles, the status of a light source as an on-axis light source or an off-axis light source does not change with movement of the retroreflector. It should be noted that this relationship is still maintained when the retroreflector is moved in a direction having a component perpendicular to the plane of the figure.

Referring back to FIG. 1, the image collection system 104A is used to collect at least two sets of image data. The first set of image data is collected in response to light at wavelength λ1 generated by light source 110 and the second set of image data is collected in response to light of wavelength λ2 generated by light source 112. The first set of image data, referred to herein as the on-axis image data, is representative of light of wavelength λ1 that reflects off the retroreflector 102 and any other objects that are illuminated by light source 110. The second set of image data, referred to herein as the off-axis image data, is representative of light of wavelength λ2 that reflects off the retroreflector and any other objects that are illuminated by light source 112. Because the on-axis illumination angle is closer to the detection angle than the off-axis illumination angle, the on-axis image data will include a stronger indication of the retroreflector relative to the off-axis image data. In this case, the intensity of light reflected by the retroreflector to the imager 108 will be much greater at wavelength λ1 than at wavelength λ2. Therefore, the intensity values at data points related to the retroreflector will be higher in the on-axis image data than at corresponding data points in the off-axis image data. FIG. 4 depicts light 122, 124, 126 of wavelength λ1 and wavelength λ2 that is incident on the imager after reflecting off the retroreflector and other objects 128. While the intensity of light 126 reflected by the retroreflector to the imager will be much greater at wavelength λ1 than at wavelength λ2, the intensity of light 122, 124 reflected by the other objects will be roughly the same assuming that the intensity of the light emitted by the two light sources is roughly equal.

The difference in the intensities of light that is reflected from the retroreflector 102 at the two wavelengths is used to generate position information. The basic operation of the system of FIG. 1 is described with reference to FIG. 5. In FIG. 5, a retroreflector 102 is connected to a pointing device 130 that is held in a hand 132. The hand, pointing device, and retroreflector are illuminated by light sources 110 and 112 from FIG. 1. On-axis and off-axis image data 136, 138 are collected by the imager while the objects are illuminated by the respective light sources. As illustrated in FIG. 5, the on-axis image data 136 includes light that reflects off the hand, the pointing device, and the retroreflector. Because the illumination angle at wavelength λ1 and the detection angle are similar, the on-axis image data includes a strong indication of light from the retroreflector. The strong indication of light is represented in FIG. 5 by a dark spot. The off-axis image data 138 also includes light that reflects off the hand, the pointing device, and the retroreflector. However, because the off-axis image data is obtained in response to off-axis light, the intensity of the off-axis light that reflects off the retroreflector towards the imager 108 is small compared to the intensity of the on-axis light that reflects off the retroreflector towards the imager. Therefore, in the off-axis image data, the retroreflector does not appear significantly brighter than any of the other objects.

In comparing the on-axis image data 136 to the off-axis image data 138, the only significant difference between the two data sets (assuming the data sets are captured simultaneously or nearly simultaneously) is the indication of the retroreflector 102. In view of this, the position of the retroreflector can be definitively identified by taking the difference between the two sets of image data to produce a difference image 140. Because most of the data points in the two sets of image data are the same, most of the corresponding data points will cancel each other out, with the one exception being the data points that correspond to the retroreflector. Therefore, the difference between the on-axis image data and off-axis image data gives a definitive indication of the retroreflector's position. As depicted in FIG. 5, the difference image definitively identifies the retroreflector while excluding any of the other objects. Referring back to FIG. 1, the difference operation is carried out by the processor 106.

Because a difference function is relied upon to generate position information, it is important to generate two sets of image data that can be efficiently compared. In one embodiment, light detected by the imager is filtered to limit the detected light to wavelength bands around the wavelengths used for illumination. For example, when light of wavelengths λ1 and λ2 is used for illumination, a bulk filter with transmission peaks at wavelengths λ1 and λ2 can be located in front of the imager to filter out light of other wavelengths (e.g., ambient light).

The imager can be configured to distinguish light of the two wavelengths used for illumination. This can be done, for example, by locating a checkerboard filter pattern in front of the imager. An example of a hybrid filter for an imager that includes a bulk filter with two peaks and a checkerboard filter pattern is described in U.S. patent applications both entitled “Method and system for wavelength-dependent imaging and detection using a hybrid filter,” application Ser. No. 10/739,831, filed on Dec. 18, 2003 and application Ser. No. 10/843,517, filed on May 10, 2004, both of which are assigned to the assignee of the current invention and incorporated by reference herein. FIG. 19A depicts a top view of imager 108 that includes a checkerboard filter pattern. In the embodiment of FIG. 19A, some imager pixels are covered by filters 111 (represented by the light squares) that pass light at wavelength λ1 and the other imager pixels are covered by filters 113 (represented by the dark squares) that pass light at wavelength λ2. FIG. 19B depicts a side view of the imager from FIG. 19A with a hybrid filter 115 located in front of the imager. The hybrid filter includes a bulk filter 117 and the wavelength-selective filters 111, 113. In another embodiment, only one set of squares (e.g., either the light or dark squares) includes a wavelength-selective filter. Using a hybrid filter, the imager can simultaneously generate the two sets of image data while the retroreflector is illuminated by reflected light from both light sources.

Alternatively, the two sets of image data can be collected sequentially. For example, the imager and light sources can be coordinated so a first set of image data is collected while only the first light source is activated and the second set of image data is collected while only the second light source is activated. The sequential activation of light sources and collection of the image data can be controlled by the processor. Although one example of sequentially collecting the two sets of image data is described, other sequential collection techniques are possible.

Although the two sets of image data essentially cancel each other out in all areas except at the retroreflector, there are usually small differences in light intensity at the non-retroreflector data points. These intensity differences are insignificant in comparison to the intensity differences at the data points that correspond to the retroreflector. In an embodiment, difference processing includes utilizing a threshold function to eliminate insignificant data points. FIG. 6 is an exemplary graph of difference image data with the intensity difference values on the x-axis and the number of data points collected at each intensity difference value on the y-axis. Note that the data points can be corrected to deal with negative intensity difference values. As represented by the peak 144 in the graph, most of the data points are clustered together. These data points represent the areas where the two sets of image data are roughly equivalent and essentially, but not completely, cancel each other out. There is another smaller cluster of data points 146 located where the intensity difference values are greater. This smaller cluster of data points corresponds to the light that is reflected from the retroreflector. As described above, the intensity difference values at these data points are larger because of the on-axis versus off-axis effect.

In order to easily separate the insignificant intensity difference values (i.e., the difference values that do not correspond to the retroreflector) from the significant intensity difference values (i.e., the difference values that do correspond to the retroreflector), a threshold difference value is established below which intensity difference values are considered insignificant and above which intensity difference values are considered significant. As represented by the dashed line 148 in FIG. 6, the threshold difference value is established at an intensity between the two clusters of data points 144, 146. In an embodiment, the threshold difference value is pre-established or set from characteristics of current or prior frames and is used to simplify the difference processing. In particular, the processor can be configured to discard all intensity difference values that are below the threshold difference value. Some artifacts 147 may remain after all the intensity difference values below the threshold difference value are discarded. Discarding insignificant data points reduces the memory requirements of the processor and enables faster processing and less latency. In one embodiment, the image processing time is reduced by processing only portions of an image that are near to where the retroreflector was previously found.

Intensity difference values that are determined to be significant are processed to identify the retroreflector. For example, all of the significant intensity difference values are processed to identify the center of the retroreflector. The location of the retroreflector's center can then be forwarded to a computer system through, for example, a universal serial bus (USB) interface. The processor may perform additional processing including, for example, confirming that the features of the retroreflector in the difference image match the known retroreflector characteristics and confirming that a pattern of potential retroreflector positions in the difference image conforms to a known pattern of positions. For example, the difference image may be compared to known image information to determine if features in the difference image match features of the retroreflector or retroreflectors.

Characteristics of the lighting can be established to provide good image data. FIG. 7 depicts an alternative embodiment of the image collection system 104A from FIG. 1 in which the image collection system 104B includes one imager 108, multiple on-axis light sources 110, and multiple off-axis light sources 112. In this embodiment, light sources 110 generate light at wavelength λ1 and are located closer to the imager than light sources 112, which generate light at wavelength λ2. The multiple light sources are used to improve the field of illumination of the image collection system over the system of FIG. 1. The on-axis and off-axis image data are collected and processed as described above with reference to FIG. 1. Although two examples of light source configurations are described with reference to FIGS. 1 and 7, other configurations can be used.

Although one exemplary image collection system 104A is described with reference to FIG. 1, many alternative embodiments of the image collection system are possible. All embodiments of the image collection system collect at least two sets of image data, where one set of image data includes a stronger indication of the retroreflector 102 than the other set of image data. As shown below, two sets of image data can be collected in many different ways.

FIG. 8 depicts an embodiment of an image collection system 104C that includes two imagers 108A, 108B and a single light source 110. The single light source provides light at wavelength λ1 and is located closer to imager 108A than to imager 108B such that the difference between the illumination angle and the detection angel at imager 108A is smaller than the difference between the illumination angle and the detection angle at imager 108B. Because of the location of the light source relative to the two imagers, on-axis image data is collected at imager 108A and off-axis image data is collected at imager 108B. Once the on-axis and off-axis image data is collected, it is processed as described above to generate position information.

FIG. 9 depicts an alternative embodiment of the image collection system 104D that includes two imagers 108A, 108B and light sources 152, 154 that provide light of two different wavelengths. In particular, two light sources 152 that generate light at wavelength λ1 are located nearer to imager 108A than to imager 108B and two light sources 154 that generate light at wavelength λ2 are located nearer to imager 108B than to imager 108A. With respect to light of wavelength λ1, on-axis image data is collected at imager 108A and off-axis image data is collected at imager 108B. With respect to light of wavelength λ2, on-axis image data is collected at imager 108B and off-axis image data is collected at imager 108A. The configuration of FIG. 9 enables two different sets of on-axis image data and two different sets of off-axis image data to be collected. The two imagers and the two different sets of on-axis image data and off-axis image data can be used to generate position information in three dimensions using stereo processing or simplified stereo processing techniques. In an embodiment, the image collection system is configured in an epipolar geometry relative to the retroreflector. FIG. 10 is a perspective view of the image collection system 104D of FIG. 9 configured in an epipolar geometry. Given the epipolar geometry, the x, y, and z coordinates of the retroreflector 102 at position M can be calculated by first determining the positions m1 and m2 of the retroreflector 102 on the imagers 108A, 108B.

In another alternative embodiment, the image collection system includes a wavelength-selective filter associated with the retroreflector. For example, the filter may cover the retroreflector. FIG. 11 depicts an embodiment of an image collection system 104E that includes on-axis and off-axis light sources 110, 112 and a wavelength-selective filter 158 covering the retroreflector. In the embodiment of FIG. 11, the wavelength-selective filter is transmissive at wavelength λ1 and blocking at wavelength λ2. By transmitting light at wavelength λ1 and blocking light at wavelength λ2, the wavelength-selective filter provides a higher intensity contrast at the data points corresponding to the retroreflector.

Because a wavelength-selective filter associated with the retroreflector can filter one of the wavelengths of light emitted by the light sources, the two sets of image data can be generated with the light sources at the same illumination angle. FIG. 12 depicts an exemplary embodiment of an image collection system 104F in which the light sources 110, 112 of two different wavelengths have similar illumination angles. In the example of FIG. 12, the wavelength-specific filter 158 associated with the retroreflector 102 is highly transmissive at wavelength λ1 and blocking at wavelength λ2. A first set of image data is collected in response to reflected light at wavelength λ1 and a second set of image data is collected in response to reflected light at wavelength λ2. Because the wavelength-selective filter associated with the retroreflector is highly transmissive at wavelength λ1 and blocking at wavelength λ2, the first set of image data includes a stronger indication of the retroreflector than the second set of image data. The two sets of image data are processed as described above to generate position information.

In another alternative embodiment, the image collection system includes one imager and one light source. FIG. 13 depicts an embodiment of an image collection system 104G that includes one imager 108 and one on-axis light source 110. The light source generates light at wavelength, λ1, and the imager is configured with a checkerboard filter, as described above, in which half of the checkerboard squares pass light at wavelength λ1 and half of the squares block light at wavelength λ1. Given this configuration, a first set of image data is generated in response to light at wavelength λ1 and a second set of image data is generated in response to ambient light minus light at wavelength λ1. Because the light source is on-axis, the first set of image data includes a stronger indication of the retroreflector than the second set of image data. In an embodiment, a wavelength-selective filter is located between the retroreflector and the imager. The wavelength-selective filter passes light at wavelength λ1 and blocks light at other wavelengths. As described above with reference to FIGS. 11 and 12, the wavelength-selective filter provides a higher intensity contrast at the data points corresponding to the retroreflector.

FIG. 14 depicts another embodiment of a single light source image collection system. The image collection system of FIG. 14 utilizes two separate imagers 108A and 108B to collect the two sets of image data. In particular, on-axis image data is collected at imager 108A and off-axis image data is collected at imager 108B. Again, a wavelength-selective filter can be located between the retroreflector and the imager to pass light at wavelength λ1.

Although the reflective element is described above as a retroreflector, a reflector other than a retroreflector can be used instead of the retroreflector. FIG. 15 depicts an embodiment of a system for generating position information that utilizes a mirror 160 instead of a retroreflector. As illustrated in FIG. 15, the off-axis light 116 is reflected by the mirror at an angle of reflection equal to the angle of incidence. Reflecting the off-axis light at this angle of reflection causes the reflected off-axis light to miss the imager 108. On the other hand, the mirror reflects on-axis light 114 back towards the imager, thus enabling the generation of two sets of image data, where one set of image data includes a stronger indication of the reflector than the other set of image data. In this configuration, the mirror is oriented such that it reflects one of the two light beams back to the imager. Alternatively, the system can be configured such that the mirror reflects light from light source 112 back towards the imager instead of light from light source 110.

A retroreflector can be used in a pointing application, for example, as a mouse in a GUI-based computer. In an embodiment, the retroreflector constitutes part of a pointing device that can be held and or moved by a user. When used in a pointing application, it is desirable to have the ability to emulate certain commands via the pointing device. For example, it is desirable to be able to convey conventional mouse functions such as “clicking,” “dragging,” “scrolling,” and lift detection.

Some conventional mouse functions can be emulated by configuring the pointing device and the retroreflector such that the retroreflector can be shielded or revealed in response to an action by the user. In one embodiment, the retroreflector is shielded or revealed by a mechanism that is activated by the user. FIGS. 16A and 16B depict an embodiment of a pointing device 170 that incorporates a mechanism for shielding or revealing a retroreflector. The pointing device includes a retroreflector 102 (FIG. 16B), a cover 172, guides 174, a finger recess 176, and a return spring 178. In FIG. 16A the retroreflector (not shown) is shielded by the cover. The user can reveal the retroreflector by moving the cover with the movement of a finger engaged with the finger recess 176. FIG. 16B shows the cover after it has been moved to reveal the retroreflector.

FIGS. 17A and 17B depict an embodiment of a pointing device 180 that incorporates a mechanism for shielding and revealing multiple retroreflectors. The pointing device includes a cover 182, multiple retroreflectors 102, and a linear-to-rotation conversion mechanism 184. The linear-to-rotation conversion mechanism includes an axle 186, pivoting joints 188, a slider 173, guides 174, and a finger recess 176. In FIG. 17A the retroreflectors are shielded by the cover. A user can reveal the retroreflectors using the linear-to-rotation conversion mechanism to rotate the cover. In FIG. 17B the cover has been rotated using the linear-to-rotation conversion mechanism to reveal the retroreflectors through holes in the cover.

In another embodiment, the retroreflector is shielded or revealed by a combination of the structure and orientation of the pointing device. For example, at least one retroreflector is located at the bottom of a cavity defined in the pointing device such that the retroreflector is shielded from illuminating light by the cavity walls when the pointing device is at some orientations with reference to the illuminating light and is exposed to the illuminating light when the pointing device is at other orientations. FIGS. 18A and 18B depict an embodiment of a pointing device 190 that includes a retroreflector 102 located at the bottom of a cavity 192 of the pointing device. When the cavity is not aimed towards the illumination light, the retroreflector is shielded by the wall of the cavity and is not illuminated. When the cavity is aimed towards the illuminating light, the retroreflector is illuminated. FIG. 18A depicts the pointing device oriented such that the illuminating light 194 is not incident on the retroreflector and FIG. 18B depicts the pointing device oriented such that the illuminating light is incident on the retroreflector.

Although some examples of techniques for shielding and revealing a retroreflector are described with reference to FIGS. 16A-18B, many other configurations are possible. In another alternative embodiment, some conventional mouse functionality can be achieved by changing some characteristic of the retroreflector or retroreflectors to emulate a mouse function. For example, the shape, size, and/or pattern of a retroreflector or retroreflectors can be changed to emulate a mouse function. In another alternative embodiment, some functionality can be achieved by gradually revealing or shielding a retroreflector. For example, the scrolling speed can be increased as more of a retroreflector is revealed or decreased as more of the retroreflector is shielded.

The above-described techniques for generating position information can be incorporated into a position tracking system for a GUI-based computer. FIGS. 20-23 depict examples of an image collection system and a pointing device integrated with a computer system. FIG. 20 depicts a portable or “laptop” computer 200 configured with an image collection system that includes two light sources 110, 112 and an imager 108 mounted in the housing of the computer. The first light source 110 is an on-axis light source that generates light at wavelength λ1 and the second light source 112 is an off-axis light source that generates light at wavelength λ2. The configuration of the image collection system is similar to that of FIG. 1 with the processor 106 being included within the computer. A pointing device 130 that includes a retroreflector 102 is used to indicate position in a GUI-based operating system. Position of the pointing device is determined as described above.

FIG. 21 depicts a portable computer 200 configured with an image collection system that includes two light sources 152, 154 and two imagers 108A, 108B mounted in the housing of the computer. The configuration of the image collection system is similar to that of FIG. 9. Given this configuration, stereo processing can be used to determine the three-dimensional position of the pointing device.

FIGS. 22A and 22B depict front and side views of an embodiment of an image collection system in which an imager 108 and light sources 110 and 112 are incorporated into a free standing housing 202. Referring to FIG. 22A, light sources 110 emit light at wavelength λ1 and light sources 112 emit light at wavelength λ2. Referring to FIG. 22B, the retroreflector is covered with a wavelength-selective filter that is transmissive at wavelength λ1 and blocking at wavelength λ2. The operation of this configuration is similar to the configuration described above with reference to FIG. 12. Specifically, a first set of image data is collected in response to reflected light at wavelength λ1 and a second set of image data is collected in response to reflected light at wavelength λ2. Because the wavelength-selective filter associated with the retroreflector is transmissive at wavelength λ1 and blocking at wavelength λ2, the first set of image data includes a stronger indication of the retroreflector than the second set of image data. The two sets of image data are processed as described above to generate position information. The image collection system depicted in FIGS. 22A and 22B can be used in conjunction with a computer. For example, the image collection system can be connected to a computer through a wired USB connection or a wireless connection. In an embodiment, the head 203 of the housing can be rotated to change the field of view of the light sources and imager. For example, the head can be rotated downward to, for example, bring a desktop that is used for mouse navigation into view.

FIG. 23 depicts a process flow diagram of a method for generating position information. At block 220, a reflector is illuminated. At block 222, a first set of image data and a second set of image data are generated. The first set of image data includes a stronger indication of the reflector than the second set of image data. At block 224, position information related to the reflector is generated using the first set of image data and the second set of image data.

FIG. 24 depicts a process flow diagram of another method for generating position information. At block 230, a pointing device that includes a retroreflector is illuminated. At block 232, on-axis image data is generated in response to the illumination. At block 234, off-axis image data is generated in response to the illumination. At block 236, position information related to the retroreflector is generated using the on-axis image data and the off-axis image data.

Because the image collection system does not rely on reflections from a desktop surface as is the case in conventional optical mouse devices, the position of the pointing device can be tracked even when the pointing device sits on a non-reflective surface or a microscopically smooth surface such as glass.

Although the system for generating position information is described with reference to pointing applications for GUI-based computer operating systems, the above-described technique for generating position information can be used in other applications that involve determining the position of an object. One application includes, for example, tracking the motion of a body part for use in motion capture or game playing.

Another advantage of the above-described dual image position tracking technique is that the use of a reflector or a retroreflector allows the image data to be collected with reduced exposure time compared to conventional digital photography exposure times.

Although the retroreflectors are described as being attached to a pointing device, the retroreflectors could be integrated with some other objects. For example, the retroreflectors can be attached to clothing, to parts of the body, or any other object whose position and/or orientation is of interest.

An object in free space can be characterized in terms of six degrees of freedom, including three degrees of freedom in translation (e.g., the x, y, and z axes) and three degrees of freedom in rotation (e.g., rotation about the x, y, and z axes). The position of an object can be characterized in terms of, for example, the x, y, and z axes. The orientation of an object can be characterized in terms of, for example, rotation around the x, y, and z axes.

The technique described above with reference to FIGS. 1-24 focuses primarily on generating position information related to an object, for example, the two-dimensional position of an object in terms of the x and y axes or the three-dimensional position of an object in terms of the x, y, and z axes. In some applications, it is desirable to determine the orientation of an object either alone or in conjunction with the position of the object. In accordance with the invention, generating orientation information involves capturing two sets of image data using at least one reflector with an orientation-specific characteristic or a reflector integrated into a device that includes some orientation-specific structural feature. The two sets of image data are then used to generate orientation information. In particular, the difference is taken between the two sets of image data and because the image data is captured using a reflector with an orientation-specific characteristic or a reflector integrated into a device that includes an orientation-specific structural feature, the resulting difference image includes orientation-specific image information related to the orientation of the reflector.

Orientation-specific image information can be generated, for example, using a retroreflector with an orientation-specific shape, using multiple retroreflectors in an orientation-specific arrangement, or by locating one or more retroreflectors at the bottom of respective cavities of a pointing device such that the retroreflectors are illuminated only in certain orientations. Various examples of techniques for generating orientation-specific image information are described below with reference to FIGS. 25A-36. In particular, FIGS. 25A-27B depict examples of a retroreflector or multiple retroreflectors that have an orientation-specific characteristic, FIGS. 28A-32B depict examples of a retroreflector or retroreflectors integrated into a pointing device that includes some orientation-specific structural feature, and FIGS. 33A and 33B depict a pointing device that includes a combination of an orientation-specific pattern of retroreflectors and a pattern of retroreflectors integrated into a pointing device that includes orientation-specific structural features.

FIGS. 25A and 25B depict an example of a retroreflector 300 that has an orientation-specific shape, in this case an arrow. Difference images formed in response to this retroreflector are unique at every orientation of the retroreflector about the z axis. That is, the retroreflector has a rotationally asymmetric shape. In FIG. 25A the arrow points straight up and in FIG. 1B the arrow is rotated approximately forty-five degrees clockwise. The image of the arrow is identified by capturing two sets of image data and taking the difference between the two sets of image data. The orientation of the retroreflector can be determined by comparing the difference image to known image information. For example, the known image information is an image of the arrow in a known orientation. The known image and the difference image can be matched to determine orientation. For example, the rotation needed to match the difference image to the known image gives an indication of the orientation of the retroreflector. In the embodiment of FIGS. 25A and 25B, the retroreflector is located on the surface of a pointing device 302.

FIGS. 26A and 26B depict an example of multiple retroreflectors having the same shape but configured in an orientation-specific arrangement on the surface of a pointing device 302. In particular, the pattern includes three retroreflectors with a single retroreflector at the top of the pattern and two retroreflectors nearby each other at the bottom of the pattern. Difference images formed in response to this pattern of retroreflectors are unique at every orientation of the arrangement about the z axis. For example, in the orientation of FIG. 26A, the single retroreflector is at the top of the pattern and the two nearby retroreflectors are at the bottom of the pattern. In the orientation of FIG. 26B, the pattern is rotated about the z axis by about ninety degrees clockwise such that the single retroreflector is at the right of the pattern and the two nearby retroreflectors are at the left of the pattern.

FIGS. 27A and 27B depict an example of multiple retroreflectors 300 that have different shapes in an orientation-specific arrangement. In the example of FIG. 27A and 27B, the retroreflectors are in the shape of a square, a circle, a triangle, and a diamond. Difference images formed in response to this pattern of retroreflectors are unique in every orientation about the z axis because the different shapes are in different locations in every orientation.

FIGS. 28A-28C depict an example of a retroreflector 310 that is integrated into a device 302 that has an orientation-specific structural feature. In the example of FIGS. 28A-28C, the device is a pointing device and the orientation-specific structural feature is a cavity 304 that extends into the pointing device from one of its surfaces. The cavity is defined by cavity walls 312 and the retroreflector 310 is located at the bottom of the cavity. FIG. 28A depicts a side view of the pointing device that identifies the cavity and the retroreflector located at the bottom of the cavity. FIG. 28B depicts a side perspective view of the pointing device, the cavity, and the retroreflector relative to a beam 308 of light. In FIG. 28B, the cavity and retroreflector are oriented relative to the beam of light such that the retroreflector is illuminated by the beam of light. Light that illuminates the retroreflector is reflected back in the same direction it is received. If the orientation of the cavity and the retroreflector relative to the beam of light changes enough, then the beam of light is blocked by some portion of the pointing device such that the retroreflector is not illuminated. In orientations other than that shown in FIG. 28B, the orientation-specific structural feature occludes the retroreflector at least in part. FIG. 28C depicts a side perspective view of the pointing device in which the cavity and the retroreflector are oriented relative to the beam of light such that the retroreflector is not illuminated. Given the configuration of FIGS. 28A-28C, a stronger indication of the retroreflector will be present in the difference image when the cavity and retroreflector are aligned with the beam of light as shown in FIG. 28B than in the difference image that is generated when the cavity and retroreflector are not aligned with the beam of light as shown in FIG. 28C. The rotational orientation of the retroreflector and the pointing device about the x and y axes can be characterized based on the existence of the retroreflector in the difference image.

In the embodiment of FIGS. 28A-28C, the alignment of the pointing device is a binary characterization. That is, the pointing device is determined to be either aligned with the beam of light when a strong indication of the retroreflector is present in the difference image or not aligned with the beam of light when a strong indication of the retroreflector is not present in the difference image. In another embodiment, the orientation between the cavity, the retroreflector, and the beam of light can be determined from the shape of the retroreflector in the difference image or from the intensity values of data points in the difference image that are related to the retroreflector. For example, in one embodiment, a partial image of the retroreflector can be used to determine orientation. In another embodiment, the intensity of the detected light from the retroreflector can be used to determine orientation. The intensity of the detected light from the retroreflector can change as the distance between the retroreflector and the imager changes and/or as orientation-specific structural features reveal or block the retroreflector as the orientation of the pointing device changes. Note that orientation can be determined from the shape of a retroreflector regardless of distance by comparing the ratio of height to width of the image.

In the example of FIGS. 28A-28C, the orientation of the pointing device 302 is determined relative to rotation around the x and y axes. As described above, the retroreflector 310 disappears from the difference image as the pointing device is tilted to the point where the retroreflector is no longer illuminated. In some applications it is desirable to simultaneously track the position and the orientation of a pointing device. The position of the pointing device in FIGS. 28A-28C cannot be tracked using the above-described dual image technique when the retroreflector is not illuminated.

In an embodiment, an additional retroreflector that is not subject to the orientation-specific structural feature of the pointing device is placed on a surface of the pointing device to enable position tracking. FIGS. 29A-29C depict an embodiment of a pointing device 302 that is similar to the pointing device described with reference to FIGS. 28A-28C except that it includes a retroreflector 300 that is not subject to the orientation-specific structural feature of the pointing device. Referring to FIG. 29A, the additional retroreflector is located on the outer surface 314 of the pointing device. When the pointing device is oriented as shown in FIG. 29B, both the retroreflector 300 on the outer surface of the pointing device and the retroreflector 310 in the cavity 304 of the pointing device are illuminated by the beam 308 of light. Because both retroreflectors are illuminated, they will both be represented in the difference image. When the pointing device is oriented as shown in FIG. 29C, the retroreflector 300 on the outer surface of the pointing device is illuminated but the retroreflector 310 in the cavity is not illuminated because the beam of light is blocked by a structural feature of the pointing device. Even though the orientation of the pointing device in FIG. 29C prevents the retroreflector 310 within the cavity from being illuminated, the retroreflector 300 on the outer surface of the pointing device is still illuminated and can be used for position tracking. The dimensions and wall angles of the cavity can be configured to set the field of view of the retroreflector.

FIGS. 30A and 30B depict an embodiment of a pointing device 302 in which multiple retroreflectors 310 are used in conjunction with orientation-specific structural features 324 to enable the generation of orientation information. In the embodiment of FIGS. 30A and 30B, multiple retroreflectors 310 are located in respective cavities. The cavities are arranged in a circle 325. Each cavity has its own orientation-specific sensitivity and the orientation of the pointing device can be determined from the locations of the retroreflectors that are represented in the difference image. Referring to FIG. 30B, the orientation-specific sensitivity of the cavities is achieved by forming cavity walls 326 and 328 at different angles. As depicted in FIG. 30B, the walls 328 of the cavities closer to the center of the circle are at a larger angle relative to a line perpendicular to the surface 314 of the pointing device than the walls 326 further from the center.

FIG. 31A depicts a side view of the pointing device 302 from FIGS. 30A and 30B in which the cavities 324 and retroreflectors 310 are oriented relative to a beam 308 of light such that all of the retroreflectors are illuminated. FIG. 31B is a front view of the pointing device from FIG. 31A in which the illumination of all of the retroreflectors is represented by the filled in dark circles. From the illumination pattern in FIG. 31B, it can be inferred that all of the cavities and retroreflectors are aligned with the beam of light. FIG. 32A depicts a side view of the pointing device from FIGS. 30A and 30B in which the cavities and retroreflectors are oriented relative to the beam 308 of light such that only some of the retroreflectors are illuminated. FIG. 32B is a front view of the pointing device from FIG. 32A in which the illuminated retroreflectors are represented by filled in dark circles and the non-illuminated retroreflectors are represented by the un-filled in circles. The orientation of the pointing device can be determined from the identity of the illuminated retroreflectors. In this embodiment, a non-illuminated retroreflector indicates that the pointing device is oriented such that the non-illuminated retroreflector has rotated towards the image collection system. Because the retroreflectors are located on the pointing device around the perimeter of circle 325, the orientation of the pointing device relative to the x and y axes can be determined. In some orientations, retroreflectors may be partially illuminated. Additional orientation information can be obtained from, for example, the shapes and/or intensity values of the image information related to the partially illuminated retroreflectors.

In another embodiment, the orientation-specific structural feature is a slot that extends into a device such as a pointing device. A retroreflector is located within the slot. Because of the shape of the slot, the field of view of the retroreflector is larger in one direction than in the other direction. Specifically, the field of view in the direction parallel to the slot is larger than the field of view in the direction perpendicular to the slot. The differences in the field of view allow the retroreflector to be illuminated over a larger range in the parallel direction and a smaller range in the perpendicular direction. A change in orientation in the perpendicular direction will be indicated by the partial or complete disappearance of the retroreflector in the difference image. Characteristics of the field of view of a retroreflector within a slot are a function of the width and depth of the slot. The dimensions and configuration of the orientation-specific structural feature can be set to achieve the desired response.

Multiple techniques for generating orientation information can be combined to enable the generation of more detailed orientation information. FIGS. 33A and 33B depict an example of a pointing device 302 that utilizes an orientation-specific pattern of retroreflectors 300 as described with reference to FIGS. 26A and 26B in conjunction with a pattern of retroreflectors 310 that is integrated into orientation-specific features 324 of the pointing device as described with reference to FIGS. 30A-32B. The configuration of FIGS. 33A and 33B enables the generation of orientation information in terms of rotation around the x, y, and z axes. In particular, the orientation-specific pattern of retroreflectors 300 on the surface 314 of the pointing device enables the generation of orientation information in terms of rotation around the z axis and the pattern of retroreflectors 310 located in the cavities of the pointing device enables the generation of orientation information in terms of rotation around the x and y axes.

FIG. 34 depicts an embodiment of a cavity 324 in a pointing device 302 and a retroreflector 310 located at the bottom of the cavity. The cavity has at least two walls 326 and 328 that have different angles relative to the axis 330 perpendicular to the surface 314 of the pointing device 302. In particular, one of the walls 326 of the cavity is at an angle that is near parallel to axis 330 and the other wall 328 of the cavity is at an angle that is non-parallel to axis 330. The angles of the walls and the depth of the cavity define the field of view of the retroreflector. Because the angles of the walls are different, the retroreflector has different fields of view at different orientations. The different fields of view are utilized as described above to give an indication of orientation. Although FIG. 34 depicts an example of a cavity, other cavity configurations are possible.

Although the cavities depicted in FIGS. 30A-33B are symmetrically oriented about a circle, the cavities could alternatively be located in a different pattern. Additionally, the field of view of the cavities can be in a different, for example, more random configuration.

FIG. 35 depicts a process flow diagram of a method for generating orientation information. At block 420, a reflector is illuminated. At block 422, a first set of image data and a second set of image data are generated, wherein the first set of image data includes a stronger indication of the reflector than the second set of image data. At block 424, orientation information related to the reflector is generated using the first set of image data and the second set of image data.

FIG. 36 depicts a process flow diagram of a method for generating position information and orientation information. At block 430, a pointing device that includes a retroreflector is illuminated. At block 432, a first set of image data is generated in response to the illumination. At block 434, a second set of image data is generated in response to the illumination. At block 436, position information and orientation information related to the retroreflector is generated using the first set of image data and the second set of image data.

Although some exemplary orientation-specific shapes and patterns of retroreflectors are described above as examples of orientation-specific characteristics, other orientation-specific configurations are possible. For example, retroreflectors in a line, a pattern of retroreflector lines, or the size of retroreflectors can be used to achieve an orientation-specific characteristic. Additionally, although some exemplary orientation-specific structural features are described above, other orientation-specific structural features are possible.

Although the retroreflectors are described as being attached to a pointing device, the retroreflectors could be integrated with some other objects. For example, the retroreflectors can be attached to clothing, to parts of the body, or any other object whose position and/or orientation is of interest.

FIGS. 37 through 44 depict embodiments of a pointing device having a powerless signal generator mechanism configured to generate a signal in response to a user action. FIG. 37 depicts a pointing device 130 that includes both a retroreflector 102 and a powerless signal generator mechanism 502. The powerless signal generator mechanism is actuated by a user action and translates the user action to a signal. The pointing device of FIG. 37 can thereby duplicate the “point-and-click” functionality of a conventional computer mouse or mouse-type interface device, but without being tethered to an external power supply and without the use of an on-board power supply such as a battery.

FIG. 38 depicts the pointing device 130 of FIG. 37 in conjunction with a computer system 100 that includes an image collection system 104, a processor 106, a GUI 105, and a receiver 103. As discussed below, a variety of signal-types can be generated by the powerless signal generator mechanism and therefore the receiver is configured to correspond to the type of signal generated by the powerless signal generator mechanism. In operation, as a user positions the pointing device, the retroreflector 102 reflects light back to the image collection system 104 and the position of the pointing device is determined as described above. When the user desires to trigger a particular function, the powerless signal generator mechanism 502 is activated by a user action. A signal is generated by the powerless signal generator mechanism in response to the user action and received by the receiver 103. The receiver notifies the processor that a particular function has been initiated. In this manner, the user can navigate screen displays or initiate programs, functions and sequences within the GUI similar to a conventional mouse.

FIG. 39 depicts an embodiment of the pointing device 130 of FIG. 37 wherein the powerless signal generator mechanism is a pulse generator 500 configured to generate a sound pulse in response to a user action. As described above in conjunction with FIG. 38, when the sound pulse is received by the receiver 103, the receiver initiates a signal to the processor 106, which triggers a function in the computer system. In an embodiment, the pulse generator utilizes a mechanically activated sonic resonator that generates a sound pulse outside the audible frequency range. Sonic resonators are well-known in the field and are not described in detail herein. Likewise, sonic receivers that can be used as receiver 103 (FIG. 38) are well-known in the field.

FIG. 40A depicts an embodiment of a pulse generator that utilizes a mechanically actuated sonic resonator 525 to generate a sound pulse. The pulse generator 500 includes an interface member shown as a push button 501 mechanically linked to an upper half of a pivot member 505. The pivot member is configured to pivot around a fulcrum 507 that is coupled to a fixed member 523 such as the casing of the pointing device. The lower half of the pivot member is coupled both to a trigger spring 509, and to a trigger 513 having a trigger release 515 at its distal end. An impulse spring 521 has a proximal end coupled to a hammer 517 and a distal end coupled to a fixed member 524 such as the casing of the pointing device. The hammer has a hammer release 519 for releasably engaging the trigger release. Prior to activation of the sonic resonator, a reset gap 511 separates the trigger release from the hammer release.

The sonic resonator 525 has an anvil surface 529 oriented along a line of travel that the hammer 517 will follow upon activation. The sonic resonator is secured in place by support members 527, which are connected to a fixed surface 531, such as the outer casing of the pointing device. The support members are configured to optimize the rate of damping of the sonic resonator, thereby ensuring that, in operation, the sound pulse is neither damped too quickly, nor too slowly. The support members are configured to minimize undesirable alterations in the frequency at which the sonic resonator resonates.

Referring to FIG. 40B, in operation, a user engages the interface member shown as pushbutton 501. The pushbutton is depressed by pressure from the user's finger 503, thereby advancing the upper half of the pivot member 505 about the fulcrum 507 and retracting the lower half of the pivot member. The lower half of the pivot member physically compresses the trigger spring 509 against the fixed surface 523. Simultaneously, the lower half of the pivot member mechanically retracts the trigger 513, forcing the trigger release 515 to engage the hammer release 519. As the actuation progresses, the retraction of the hammer progressively deforms the impulse spring 521, resulting in increasing flexure of the impulse spring 521. The impulse spring is configured to flex along a path that causes the hammer release 519 to slide downward against the front surface of the trigger release 513. The impulse spring is connected to the fixed member 524 at a position that is configured to allow disengagement of the hammer release and the trigger release at a predetermined point of flexure of the impulse spring. FIG. 40B shows the relationship of the trigger release 515 and hammer release 519 just prior to release of the hammer.

When the depression of push button 501 reaches a predetermined distance, the trigger release 513 disengages the hammer release 519. Upon release, the impulse spring 521 impels the hammer toward the anvil surface 529 of the sonic resonator 525, striking the anvil surface and causing the sonic resonator to vibrate at a predetermined frequency, thereby generating a sound pulse. The sound pulse is detected by the receiver 103 shown in FIG. 38. The receiver generates an electrical signal in response to the detected sound pulse and provides the electrical signal to the processor 106. The electrical signal is used to trigger a function in the computer system. For example, when a user positions a positioning image such as a cursor upon a select icon, hyperlink, or text portion of a graphical user interface (GUI) through use of the pointing device and activates a signal from the powerless signal generator mechanism, a user can initiate programs, functions and sequences within the computer or viewing screen. Throughout this disclosure, the depiction of a push-button interface member is exemplary. The present invention comprehends alternative manual interface devices, including, but not limited to proximity sensors, photo sensors, thermocouples, and voice activation.

Although variation exists within the range of human hearing, the upper frequency limit of the average person is somewhere in the range of 18 kHz to 20 kHz. To reduce the annoyance imposed on listeners, a sonic resonator can be utilized that is configured to resonate in the frequency range of 20 kHz to 100 kHz, thereby falling outside the audible range. Embodiments are envisioned, however, for the use of frequencies above 100 kHz, or below 20 kHz, including those in the audible range.

Because many pointing devices currently in use have multiple signal generators, such as “right click” and “left click” mouse embodiments, the present invention can be configured with multiple sonic resonators having distinct frequencies. The “left” and “right” click functions of a traditional mouse can thereby be duplicated by distinct frequencies, or distinct frequency combinations. This can be accomplished through as few as two sonic resonators of distinct frequencies, a first representing a left click function and a second representing a right click function. Distinguishable pulses can be activated by distinct interface members on the powerless signal generator mechanism or distinct actions (such as “single clicking” or “double clicking”) on a particular interface member.

It is possible that stray noise having a frequency matching the resonator frequency could trigger a false input signal. To reduce the likelihood of triggering a false input signal, an embodiment further incorporates a receiver configured to recognize an input command signal only if the sound volume of the incoming signal exceeds a minimum db threshold. If the db volume of an incoming signal does not exceed a minimum threshold volume, the receiver does not recognize an input command signal. Although there are many variables, sound dissipates at roughly the inverse square of the distance from the source. By assigning an “operational distance” as the maximum distance from a computer at which a user is likely to operate the pulse generator, and determining the detected db volume of a signal generated from that maximum distance, the receiver can be configured to recognize a valid signal only if the signal is generated within the “operational distance” of the receiver. As a result, activation of the pulse generator 500 of a pointing device by a first person will not interfere with a second computer outside the operational distance.

Even using a minimum volume threshold, however, it remains possible for stray noise of a given frequency to satisfy the minimum db threshold. An additional safeguard against a false input command can be achieved through a multi-frequency pulse generator having two or more sonic resonators that are engaged simultaneously by the activation of the same push button thereby collectively representing a single sound pulse. The receiver is configured to recognize the incoming pulse as a valid input signal only if all required frequencies are present and if those required frequencies exceed a minimum db threshold. Additionally, the receiver can be configured to recognize the incoming pulse as a valid input signal only if the db volumes of the respective frequencies are within a preset db range of each other. Assume, for example, a two frequency embodiment wherein frequencies f1 and f2 are determined to reliably remain within 3 db of each other during signal propagation. The receiver is therefore configured to recognize a valid signal only if frequencies f1 and f2 both exceed the minimum db threshold and only if f1 and f2 are within a 3 db range of each other. If a sound pulse comprises f1 and f2 and the volume of both frequencies are within 3 db of each other, the receiver will interpret the incoming signals as a command pulse generated by the pulse generator 500. However, if the respective volumes of the two frequencies are not within the exemplary 3 db range of each other, the receiver will disregard the disparate frequencies as noise and not an input command produced by sonic resonators within the pointing device. In this way, a multi-frequency pulse can provide additional safeguards against inadvertent input command activation as the result of noise.

Another advantage of using multiple sonic frequencies to signify a positive activation of a pulse generator 500 can be appreciated in forums wherein multiple persons are working with pointing devices which are all configured with pulse generators 500. If multiple pointing devices were to use the same frequency or frequency combination to represent the “right click” signal of a conventional mouse, as a first user activated a first pulse generator 500 to trigger a response by a first computer, the signal could have the undesirable effect of inputting a signal to a second computer. By fabricating each pointing device with a plurality of sonic resonators 525, different pointing devices can be configured to activate different combinations of sonic resonators. As long as two users who are proximate each other use a different combination of frequencies, no interference between the two users will occur.

FIG. 41 depicts eight sonic resonators 550-557 that can be incorporated within a single pointing device. The eight sonic resonators correspond to an eight-bit field 549. The bit field displays a predetermined set of ones and zeros for representing a positive activation in response to the frequency pattern of a sound pulse. Although an eight bit field technically has 2⁸ possible configurations, a binary field of all zeros would indicate that no sonic resonator had been activated. From this, it can be readily appreciated that in a pointing device having “n” sonic resonators available at distinct frequencies, the number of possible frequency combinations for representing an activation signal is equal to 2^(n)−1 different frequency combinations. According to an embodiment, each pointing device is user-configurable, thereby allowing responsive measures to be taken by a user in the event of interference with neighboring uses.

FIG. 42 depicts a pointing device 130 wherein the powerless signal generator mechanism is a piezo-electric signal generator 603. The piezo-electric signal generator is configured to generate an RF signal in response to a user action. Piezostriction is a well-known electromechanical phenomena whereby an electrical signal applied to certain crystal structures causes a physical constriction or displacement of molecular structures within the crystal. Alternatively, by applying pressure upon certain crystals, an electric signal can be generated. Current piezo technology allows the generation of a radio frequency signal, including a complex signal, such as a digital 32 bit signal, by means of a mechanically activated piezo signal generator. Radio frequency receivers that can be used as receiver 103 (FIG. 38) are well-known in the field.

FIG. 43 depicts an embodiment of a piezo-electric signal generator 603 that includes a piezo energy transducer 609 and an RF transmitter 607 that are electrically coupled by signal path 619. A mechanical interface 617 links an interface member, shown as push button 501, to the piezo energy transducer. When a user depresses the push button, the force of the depression is transmitted through the mechanical interface 617 to the piezo energy transducer 609, imparting a force on the piezo energy transducer which results in the generation of electrical energy. The electrical energy is processed by the RF transmitter into an RF signal of appropriate signal attributes. Signal attributes can include, but are not limited to frequency, bit field size, and a pre-configured binary code. As noted above, an exemplary signal can have a 32 bit signature.

As discussed in conjunction with FIG. 38, the piezo-electric signal generator is used in conjunction with a pointing device 130 having a retroreflector 102 which reflects light to the image collection system 104. In operation, as the user moves the pointing device 130, the processor 106 correlates the position of the retroreflector 102 with a position on the GUI 105 (FIG. 38) and generates a positioning image such as a cursor or arrow on the GUI. When the user has positioned the positioning image over a desired icon, image or text area on the GUI, the user engages the push button 501 to activate the piezo-electric signal generator 603. The piezo-electric signal generator generates an RF signal that is transmitted to the receiver 103. In response, the receiver forwards a corresponding signal to the processor to trigger a function in the computer system.

FIG. 44 depicts a process flow diagram of a method of generating position information relating to a pointing device. At block 701, a reflector that is incorporated into a pointing device is illuminated. At block 703, the image collection system generates image data that includes an indication of the reflector. At block 705, position information relating to the reflector is generated using the image data. At block 707, a signal is generated from the pointing device using energy provided from a user action. At block 709, the signal is detected. At block 711, a function is initiated in response to the detection of the signal.

As used throughout this disclosure, the terms “computer” and “computer system” are used in the broadest sense, and include any electronic device incorporating digital logic and utilizing a GUI. Examples fitting this generic description of a “computer” include, but are not limited to, standard PCs and McIntosh computers, digital televisions, X-boxes and game stations, PDA (pocket digital assistants), Blackberry devices, cell phones, fax and copy devices having on-board display screens, and programmable controllers. Although specific embodiments of the invention have been described and illustrated, the invention is not to be limited to the specific forms or arrangements of parts so described and illustrated. The scope of the invention is to be defined by the claims appended hereto and their equivalents. 

1. A system for generating position information related to a pointing device, the system comprising: the pointing device comprising; a reflector; and a powerless signal generator mechanism configured to generate a signal in response to a user action, wherein the signal triggers a function in a computing system; an image collection system configured to generate a first set of image data and a second set of image data, wherein the first set of image data includes a stronger indication of the reflector than the second set of image data; a processor configured to use the first set of image data and the second set of image data to generate position information related to the reflector, wherein the processor is configured to take the difference between the first set of image data and the second set of image data wherein taking the difference between the first set of image data and the second set of image data comprises taking the difference between corresponding data points of the first and second sets of image data such that most of the corresponding data points from the first and second sets of image data cancel each other out except for data points that correspond to the reflector; and a receiver configured to detect the signal from the powerless signal generator mechanism.
 2. The system of claim 1 wherein the powerless signal generator mechanism is a pulse generator that generates a sound pulse in response to the user action.
 3. The system of claim 2 wherein the pulse generator comprises a sonic resonator and a hammer configured to engage the sonic resonator.
 4. The system of claim 2 wherein the sound pulse includes a sound pulse in the 20 kHz to 100 kHz range.
 5. The system of claim 1 wherein the pointing device further comprises a second powerless signal generator mechanism configured to generate a second signal in response to a user action.
 6. The system of claim 5 wherein the powerless signal generator mechanisms are configured such that the first and second signals have a distinguishable attribute.
 7. A system for generating position information related to a pointing device, the system comprising: a computing system that utilizes a graphical user interface (GUI); the pointing device for use with the GUI, the pointing device comprising; a reflector; and a powerless signal generator mechanism configured to mechanically generate a signal in response to a user action, wherein the signal is generated to trigger a first function of the GUI; an image collection system configured to generate a first set of image data and a second set of image data, wherein the first set of image data includes a stronger indication of the reflector than the second set of image data; a processor configured to use the first set of image data and the second set of image data to generate position information related to the reflector for use in navigating within the GUI, wherein the processor is configured to take the difference between the first set of image data and the second set of image data wherein taking the difference between the first set of image data and the second set of image data comprises taking the difference between corresponding data points of the first and second sets of image data such that most of the corresponding data points from the first and second sets of image data cancel each other out except for data points that correspond to the reflector; and a receiver configured to detect the signal from the powerless signal generator mechanism and to provide the detected signal to the computing system to trigger the first function of the GUI.
 8. The system of claim 7 wherein the powerless signal generator mechanism is a pulse generator that generates a sound pulse in response to the user action.
 9. The system of claim 7 wherein the pointing device further comprises a second powerless signal generator mechanism configured to generate a second signal in response to a user action, wherein the second signal is generated to trigger a second function of the GUI.
 10. The system of claim 9 wherein the powerless signal generator mechanisms are configured such that the first and second signals have a distinguishable attribute.
 11. A method for generating position information related to a pointing device, the method comprising: illuminating a reflector that is incorporated into the pointing device; generating a first set of image data and a second set of image data, wherein the first set of image data includes a stronger indication of the reflector than the second set of image data; generating position information related to the reflector using the first and second sets of image data by taking the difference between the first set of image data and the second set of image data, wherein taking the difference between the first set of image data and the second set of image data comprises taking the difference between corresponding data points of the first and second sets of image data such that most of the corresponding data points from the first and second sets of image data cancel each other out except for data points that correspond to the reflector; generating a signal from the pointing device using energy provided from a user action; detecting the signal; and initiating a function in response to detection of the signal.
 12. The method of claim 11 wherein generating the signal comprises impacting a resonator in response to the user action.
 13. The method of claim 11 further comprising: generating a second signal from the pointing device using energy provided from a user action, wherein the first and second signals have different attributes; detecting the second signal; and initiating a second function in response to detection of the sound signal. 